A. Field of the Invention
The present invention relates to devices for separating constituents from fluids, performing a dilution, and inoculating a reagent; and, more particularly, the present invention relates to a centrifuge capable of spinning and stopping rapidly with the aid of dynamic braking and a processing member mountable on the centrifuge for performing the separating, diluting and inoculating functions; and to a new and improved method of separating constituents from a fluid, performing a dilution, and inoculating a reagent.
B. Description of the Background Art
Chemical tests for analyzing fluids such as whole blood often apply centrifugal force to fluid contained in a processor card to separate constituents, such as plasma, from the fluid, mix the constituents with a diluent and combine the diluted sample with reagent. Each of the functions (separating, diluting and combining with reagent) must be performed sequentially, and this requires moving the fluid and diluent to a location, performing a function, and moving the fluid to a different location to perform the next function. Examples of devices for performing these tests are provided in U.S. Pat. Nos. 4,690,899; 3,899,296; 4,456,581; 4,557,600; and 4,515,889.
One procedure to move fluid through a processor card to perform the different functions is to change the position of the processor card on a centrifuge relative to the central axis of rotation. By changing the position of a processor card, different portions of the processor card are aligned with the radial centrifugal force vectors, thus moving the fluid in different directions.
Another procedure for separating, diluting and mixing a fluid and inoculating a reagent pad is described in European Patent Application No. 85 105 106.0, filed Apr. 26, 1985. This procedure employs a centrifuge with an assembly for rotating a processor card on the centrifuge. Rotating the processor card aligns different portions of the processor card with the centrifugal force vector. By rotating the position of a processor card on a centrifuge the centrifugal force acts on the fluid and diluent in the processor card to move the fluid and diluent in different directions within the processor card. Centrifugal force acting in a first direction, for example, will move the fluid and diluent to a first position. While the fluid and diluent are in the first position, a testing procedure can be performed. Once the testing procedure is completed, the direction of centrifugal force can be changed by turning the processor card. The centrifugal force will move the fluid and diluent to a second position for a second test.
The devices that move a processor card or change the direction of centrifugal force are expensive since they require complex movable structures More frequent servicing of these devices is also required due to the more complex structures. It is desirable to provide a system capable of moving fluids and diluents between different testing locations within a processor card without the necessity of additional structure being added to the centrifuge for maneuvering the card.